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1 package com.tirsen.nanning.samples.rmi;
2
3 import org.apache.commons.logging.Log;
4 import org.apache.commons.logging.LogFactory;
5
6 import java.util.HashMap  ;
7 import java.util.Iterator ;
8 import java.util.Map ;
9 import java.util.Collections ;
10
11 class ObjectTable {
12 private static final Log logger = LogFactory.getLog(ObjectTable.class);
13
14 private static final int DEFAULT_TIMEOUT = 60 * 60 * 1000;
15
16 private Map objectToId = Collections.synchronizedMap(new HashMap ());
17 private Map idToReference = Collections.synchronizedMap(new HashMap ());
18
19 private long currentId = 0;
20 private long timeout;
21
22 public ObjectTable() {
23 this(DEFAULT_TIMEOUT);
24 }
25
26 public ObjectTable(long timeout) {
27 this.timeout = timeout;
28 }
29
30 Object getFromID(Object id) {
31 LocalReference o = (LocalReference) idToReference.get(id);
32 assert o != null;
33 o.touch();
34 cleanupStale();
35 return o.getReferred();
36 }
37
38 private synchronized void cleanupStale() {
39 try {
40 for (Iterator i = idToReference.values().iterator(); i.hasNext();) {
41 LocalReference ref = (LocalReference) i.next();
42 if (ref.isStale(timeout)) {
43 if (logger.isDebugEnabled()) {
44 logger.debug("Removing " + ref.getReferred());
45 }
46 objectToId.remove(ref.getReferred());
47 i.remove();
48 }
49 }
50 } catch (Exception ignore) {
51 logger.warn("Got error while cleaning out stale objects (ignored)", ignore);
52 }
53 }
54
55 synchronized Object register(Object o) {
56 Object id = objectToId.get(o);
57 if (id == null) {
58 if (logger.isDebugEnabled()) {
59 logger.debug("Registering " + o);
60 }
61 id = newId();
62 objectToId.put(o, id);
63 idToReference.put(id, new LocalReference(o));
64 }
65 return id;
66 }
67
68 private Object newId() {
69 return new Long (currentId++);
70 }
71
72 public boolean hasID(Object o) {
73 return objectToId.containsKey(o);
74 }
75
76 boolean isIDRegistered(Object id) {
77 cleanupStale();
78 return idToReference.containsKey(id);
79 }
80
81 public synchronized void clear() {
82 if (logger.isDebugEnabled()) {
83 logger.debug("Clearing");
84 }
85 objectToId.clear();
86 idToReference.clear();
87 currentId = 0;
88 }
89
90 private static class LocalReference {
91 private Object object;
92 private long lastTimeTouched;
93
94 LocalReference(Object object) {
95 this.object = object;
96 touch();
97 }
98
99 Object getReferred() {
100 return object;
101 }
102
103 void touch() {
104 lastTimeTouched = System.currentTimeMillis();
105 }
106
107 boolean isStale(long timeout) {
108 return System.currentTimeMillis() - lastTimeTouched >= timeout;
109 }
110 }
111 }
112 |
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